Opal Tower report released, ‘significant works’ required

The probable causes were isolated to localised structural design and construction issues, which included that on level 10 of the building:

• the hob beam was not completely grouted;
• reinforced steel, inadequate cover concrete and the placement of an electrical conduit were within the cover zone of the hob beam;
• an “incomplete dowel bar” that was “possibly cut during construction”;
• precast concrete panels that were larger than what the design intended; and
• reinforcing bars with a diameter of 20 millimetres were potentially used instead of the intended diameter of 28 millimetres.

The damage on level 4 is still being assessed and as such no reasons were given for this damage yet. 

Extreme weather, poor quality materials and foundation issues were ruled out as causes of the structural issues.

Next steps

The professors said major works are required to repair and strengthen damaged hob beams and in some cases the panels that rest on them.

“However, while we have isolated the probable cause to localised structural design and construction issues, we need more information to make definitive conclusions about the cause or causes of the damage to this structure and the proposed rectification,” they said.

“We agree that the structural principles behind the rectification works are sound, but recommend independent oversight and review by qualified structural engineers before any major works begin.

“We also believe more work needs to be done to check the structural design of the hob beams and associated structural members with consideration given to strengthening them wherever they are in the building.”

Can residents return?

The statement did not come to a conclusion whether residents were safe to re-occupy the building.

“Re-occupation of Opal Tower extends beyond the scope of this investigation and was a matter for residents and the builder, subject to appropriate engineering and design oversight and guarantees,” the statement from the professors read.

“More work is also needed before we can provide recommendations on what needs to happen to avoid incidents like this in future.”

Anthony Roberts, minister for planning and housing, thanked owners and residents for their patience during the investigation.

He said he was impressed with the efforts of involved parties in order to get owners and residence access back to their properties.

“I trust that this independent interim report will be an important input to the discussions between the builders, the owners’ corporation and residents about moving people back into the building,” he said.

Safety blitz in 2019

The Opal Tower, which opened in August last year, has called into question the effectiveness of NSW’s quality and safety checks.

An audit of private building certifiers will be launched by the NSW government this year, in direct response to the Opal Tower fiasco.

Certifiers are responsible for signing off on the safety and compliance of new properties. Local councils were once responsible for this process, but the industry was privatised in the early 2000s and is now, in effect, self-regulating.

The NSW government has also marked plans for a “name and shame” register of dodgy certifiers. This is one to watch for property investors, particularly if they fear their property is defective, and to check if their certifier makes the list.